Intercalation of glycine into hydroxy double salt and its adsorption performance towards Uranium(VI)

Human activities and natural processes lead to environmental water pollution by Uranium. In the field of environmental remediation, much attention has been paid to the development of an efficient adsorbent for removing uranyl ion (UO₂ ²⁺) from contaminated water. In this work, a new material was synthesized by intercalation of glycine (Gly) into zinc containing hydroxy double salt (Zn₅-NO₃), and its adsorption properties towards uranyl ion were studied in an aqueous solution. The X-ray diffraction (XRD) analysis of the composite material (Zn₅-Gly) indicated that Gly was inserted into the gallery of Zn₅-NO₃ with bilayer arrangement. The adsorption capacity of Zn₅-Gly towards UO₂ ²⁺ in an aqueous solution is 745.53 mg/g and removal rate close to 100%, these criteria make it a potential candidate for uranium removal. The adsorbent decreased 233.38 ppm of UO₂ ²⁺ to 23.47 ppm inside 120 min and finally to 0.79 ppm within 7 h. The adsorption kinetics of UO₂ ²⁺ fits with the pseudo-second-order model, suggesting a chemisorption mechanism mainly via amino and carboxyl groups interactions. The adsorption of UO₂ ²⁺ by the adsorbent was confirmed by XRD, Fourier-transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS).